Ultrabook is the latest name Intel is defining as a new market category for Laptop computers
The Intel guidelines include a low-voltage Intel Core processor, a frame no thicker than 21mm (0.83 inches), at least five hours of battery like, and lightning-fast boot times. The fast boot times rely on an Intel technology called "Rapid Start," which makes use of flash storage embedded in the laptop's motherboard. These were originally called "CULV" (Consumer Ultra Low Voltage) laptops before Intel realized that this was a terrible name but the emphasis is the same. It must feature the new Intel low-voltage hardware.
The words laptop and computer are both missing from the name which can make this easily confused with an eBook Reader but it is really a regular laptop running Windows. The definition is likely to change to include a touchscreen when Windows 8 appears with full touchscreen support.
 Detailed requirements
These are specified by Intel to qualify to use the trademarked name. The definition will change over time. Under the current Ultrabook definition:
- less than 18mm in height and have a display less than 14 inches (often 13.3 inches or less).
- Systems with 14-inch or larger displays can be up to 21mm (0.83 inches) thick typically because larger systems often have optical drives.
- An extra 2mm of thickness is allotted for touch screen laptops, hybrid, or convertible designs, as touch-enabled screens are thicker.
- must have a "fast resume," moving from a near-zero power hibernation state to the point where users can type on the keyboard in less than seven seconds.
- To do this most manufacturers will implement Intel's RapidStart, which uses a non-volatile NAND flash memory cache in addition to the main disk drive. Effectively, this stores the contents of the system's memory on a fast solid-state drive (SSD) cache that can be quite small—just the size of the system DRAM.
- must use the "Huron River" platform, based on the Sandy Bridge platform and the Cougar Point chipset, sold under the 2nd Generation Core platform label. Only Core i3, i5, and i7 qualify.
- battery life must exceed 5 hours.
- Apple MacBook Air 13-inch was the start of the whole revolution. All the other devices are chasing this one.
- HP Folio 13
- Lenovo IdeaPad U300s
- Toshiba Portege Z830-S8302
- Toshiba Portege Z835-P330 - This one is likely to make a good portable eBook Reader with its 8 hour battery life and 2.4 lb weight. It has a 13.3-inch widescreen display, with 1,366 x 768 pixel resolution.
- Asus Zenbook UX31-RSL8
- Asus UX21 Laptop
 For more information
Intel Blog - This is where the definition is specified.